Abstract
The purpose of this study was to investigate the influence of hydroxypropyl-β-cyclodextrin on diosmin, substance from the
flavones category with important pharmacological properties. We carried out solubility studies, calculating the solubility constant
of the complex formed between diosmin and hydroxypropyl-cyclodextrin at various temperatures (20, 25 and 37 0C) and in the
presence of increasing cyclodextrin concentrations. AL type curves were obtained which suggest the formation of an inclusion
compound on a 1:1 molar ratio and the solubility constants had values between 370 and 453 M-1. Knowing that between diosmin,
hydroxypropyl-cyclodextrin and the used solvent, thermodynamic interactions occur, we investigated the influence of these
interactions on several thermodynamic parameters such as Gibbs free energy change, free energy change, enthalpy change and
entropy change. The calculated values showed that the reaction is positively influenced by the cyclodextrin’s concentration
increment and the temperature, the process being spontaneously. Next, inclusion compounds were obtained by co-evaporation
and co-precipitation, and their structures were confirmed by FTIR and MS analysis. The complexes were tested in vitro
compared with the parent substances, the results indicating improved antioxidant and antimicrobial activities. Moreover, the
dissolution of diosmin increased in mediums similar to physiological conditions (simulated gastric and intestinal).